According to this list Wilhelm Borgas produced N23 which is what I see on the above badge. Borgas also used the marking of M1/23 too it appears.
The Makers list for the NSDAP party badge data base - Wehrmacht-Awards.com Militaria Forums
Response to below: Agreed, we seemed to of posted at the same time.
No way to refresh screen while typing/posting reply
I'm starting to change my opinion as if it were a "N" it would be backwards. It seems closer to a worn "M"....maybe , but considering my experience in these I'm officially retiring for the night. Good luck with identifying it guys.
I've got a similar electricity sign, except it reads ''achtung'' instead of the Polish words.
According to the seller it was removed from a German WW2 bunker after the war...